Evidence indicates a significant positive relationship between nurse staffing levels and patient outcomes. Yet there is currently no scientifically based approach to determine what level of staffing is optimal to achieve quality patient outcomes. Research is needed to identify a method to quantify demands for nursing care in varying settings and translate these into effective staffing levels. The method should be generalizable to allow nurse managers for any given unit to determine the required staffing levels to achieve quality standards. Queueing theory, which relates variable demands for service to the response times to meet those demands for a given level of staffing, is a promising methodology to accomplish this goal. Queueing models have been successfully used in many service industries and organizations. A queueing model is a mathematical representation of a service system, which takes as input the average arrival rate of demands, and the average service time to meet those demands and informs staffing based on various performance metrics. In this way, queueing models can inform decision makers on the tradeoffs between increased staffing levels and improved response times. The aims of this exploratory study are to 1) identify unit-specific time-sensitive nursing care interventions (demands) and the average times required to perform them (service times); 2) determine unit-specific volume and timing (arrival rates) for nursing care demands; 3) develop performance standards for acceptable delays for nursing care; and 4) develop and test a registered nurse staffing plan based on queueing models. Using one orthopedic nursing unit as the test site, these aims will be met using qualitative and quantitative methods. Much of the quantitative data needed for the use of queueing models will be available electronically. With increased use of information technology in hospitals, this proposal is timely in both establishing the framework for identifying, collecting and analyzing these important data as well as providing the first clinical test of the use of queueing methodology to guide nurse staffing decisions. The application of queueing models to nurse staffing is an example of a unique and innovative use of an existing methodology in a new scientific area. The proposed work described here is in the early and conceptual stages and therefore, the R21 mechanism was chosen. If the results of this study demonstrate a queueing model to be successful in informing nurse staffing decisions, further research will be proposed to test the methodology in multiple settings and a generalizable framework will be developed to assist nurse managers to use queueing models within their own settings. This study will be the first clinical test of the use of queueing methodology to guide nurse staffing decisions. A long term goal of this program of research is to improve the quality of nursing services at the bedside by developing a generalizable framework for using queueing theory to inform nurse staffing needs across a variety of settings. [unreadable] [unreadable] [unreadable]